Objective To compare the effect and characteristics of genomic DNA extraction from frozen whole blood using two different methods. Methods Genomic DNA were extracted with potassium iodide method and Promega Genomic DNA Purification Kit.The detection was performed by UV spectrophotometry, gel electrophoresis and PCR. Results The concentration of genomic DNA extracted by potassium iodide method and Promega Genomic DNA Purification Kit method was:(330.9±0.94)ng/μL and(490.3±3.16)ng/μL; and the ratio of A260/A280 was:(1.87±0.03) and(1.85±0.06).The quantity of genomic DNA extracted by kit is slightly higher than that by potassium iodide method. There is no significant difference in DNA quality and purity between two methods. Conclusion Kit is the more simple, faster, non-toxic method compared with the potassium iodide method, but the cost is expensive. Potassium iodide method is helpful to extract genomic DNA from a large number of clinical blood samples due to the low cost. Two methods are able to meet the needs of molecular biology experiments.